Negative Pressure Membrane Distillation for Excellent Gypsum Scaling Resistance and Flux Enhancement
Negative Pressure Membrane Distillation for Excellent Gypsum Scaling Resistance and Flux Enhancement
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DOI：
10.1021/acs.est.1c07144
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发表时间：
2021-12-23
影响因子：
11.4
通讯作者：
He, Tao
中科院分区：
文献类型：
--
作者：
Liu, Yongjie;Horseman, Thomas;He, Tao
膜蒸馏（MD）有可能成为一种有竞争力的技术，用于管理高盐水，但直到矿物结垢的关键挑战得到解决。用于减轻MD中的矿物结垢的最先进方法涉及使用难以制造且商业上不可用的超疏水膜。本研究探索了一种新的操作策略，即负压直接接触膜蒸馏（NP-DCMD），可以最大限度地减少矿物结垢与市售的疏水膜，并在同一时间大大提高水蒸气通量。通过在进料流上施加负表压，NP-DCMD实现了延长的抗CaSO 4结垢性和高达62%的显著蒸汽通量增强。特殊的抗结垢性归因于在负压下形成凹形液体-气体，其改变水-空气界面的位置以阻碍界面成核和晶体生长。在NP-DCMD中，显著的通量增强是由于孔内分子扩散阻力降低和边界层传热动力学增强所致。NP-DCMD在抗结垢性和蒸汽通量方面与商业膜实现了实质性的性能改进，由于其简单性和有效性，NP-DCMD是一项具有巨大实际应用潜力的重大创新。
Membrane distillation (MD) has potential to become a competitive technology for managing hypersaline brine but not until the critical challenge of mineral scaling is addressed. The state-of-the-art approach for mitigating mineral scaling in MD involves the use of superhydrophobic membranes that are difficult to fabricate and are commercially unavailable. This study explores a novel operational strategy, namely, negative pressure direct contact membrane distillation (NP-DCMD) that can minimize mineral scaling with commercially available hydrophobic membranes and at the same time enhance the water vapor flux substantially. By applying a negative gauge pressure on the feed stream, NP-DCMD achieved prolonged resistance to CaSO4 scaling and a dramatic vapor flux enhancement up to 62%. The exceptional scaling resistance is attributable to the formation of a concave liquid-gas under a negative pressure that changes the position of the water-air interface to hinder interfacial nucleation and crystal growth. The substantial flux enhancement is caused by the reduced molecular diffusion resistance within the pores and the enhanced heat transfer kinetics across the boundary layer in NP-DCMD. Achieving substantial performance improvement in both the scaling resistance and vapor flux with commercial membranes, NP-DCMD is a significant innovation with vast potential for practical adoption due to its simplicity and effectiveness.